On 5/4/20 12:26 PM, Michal Hocko wrote: > On Mon 04-05-20 12:33:04, Sandipan Das wrote: >> For unpopulated zones, the pagesets point to the common >> boot_pageset which can have non-zero vm_numa_stat counts. >> Because of this memory-less nodes end up having non-zero >> NUMA statistics. This can be observed on any architecture >> that supports memory-less NUMA nodes. >> >> E.g. >> >> $ numactl -H >> available: 2 nodes (0-1) >> node 0 cpus: 0 1 2 3 >> node 0 size: 0 MB >> node 0 free: 0 MB >> node 1 cpus: 4 5 6 7 >> node 1 size: 8131 MB >> node 1 free: 6980 MB >> node distances: >> node 0 1 >> 0: 10 40 >> 1: 40 10 >> >> $ numastat >> node0 node1 >> numa_hit 108 56495 >> numa_miss 0 0 >> numa_foreign 0 0 >> interleave_hit 0 4537 >> local_node 108 31547 >> other_node 0 24948 >> >> Hence, return zero explicitly for all the stats of an >> unpopulated zone. > > I hope I am not just confused but I would expect that at least > numa_foreign and other_node to be non zero. Hmm, checking zone_statistics(): NUMA_FOREIGN increment uses preferred zone, which is the first in zone in zonelist, so it will be a zone from node 1 even for allocations on cpu associated to node 0 - assuming node 0's unpopulated zones are not included in node 0's zonelist. NUMA_OTHER uses numa_node_id(), which would mean the node 0's cpus have node 1 in their numa_node_id() ? Is that correct? So the 108 comes from where exactly, some early allocations until all was initialized?
